Abstract
For the study of the effects of partially non-submerged rigid vegetation on the free-surface confluence flow in a curved open channel, a numerical simulation is carried out by using the Volume of Fluid model combined with the porous media model with the software OpenFOAM. The model is first validated by using available experimental measurement data with a good agreement. Then, the characteristics of the separation zone generated by the centrifugal forces and the confluence flow are analyzed. Due to the resistance created by the vegetation, the velocities in the separation zone are more chaotic and the separation zone becomes smaller and more irregular. The reduction of the separation zone area of the vegetated flow in the convex bank is more significant than that in the concave bank. The velocities in the vegetated region become much smaller and remains so in the downstream flow after the vegetation region. Meanwhile, the vegetation compresses and divides the circulations in the flow area, rebuilding a structure with smaller circulations in the main flow and unclear circulations in the vegetation region. In addition, the bed wall shear stresses are significantly smaller in the vegetation region and the separation zone compared to the non-vegetated flow. This implies that the vegetation can have the effect of protecting the river bed from erosion.
Similar content being viewed by others
References
Riley J. D., Rhoads B. L. Flow structure and channel morphology at a natural confluent meander bend [J]. Geomorphology, 2012, 163: 84–98.
Sui B., Huang S. H. Numerical analysis of flow separation zone in a confluent meander bend channel [J]. Journal of Hydrodynamics, 2017, 29(4): 716–723.
Jing H., Guo Y., Li C. et al. Three dimensional numerical simulation of compound meandering open channel flow by Reynolds stress equation model [J]. International Journal for Numerical Methods in Fluids, 2009, 59: 927–943.
Miyawaki S., Constantinescu S. G., Kirkil G. et al. Numerical investigation of three-dimensional flow structure at a river confluence [C]. 33rd International Association Hydraulic Research Congress, Vancouver, Canada, 2009.
Constantinescu G. S., Miyawaki S., Rhoads B. et al. Structure of turbulent flow at a river confluence with a momentum and velocity ratios close to 1: Insight from an eddy-resolving numerical simulation [J]. Water Resource Research, 2011, 47(5): W05507.
Ghobadian R., Tabar Z. S., Koochak P. Numerical study of junction-angle effects on flow pattern in a river confluence located in a river bend [J]. Water SA, 2016, 42(1): 43–51.
Liu N., Zhou Q., Huang S. et al. Estimation of flow direction in meandering compound channels [J]. Journal of Hydrology, 2017, 556: 143–153.
Shaheed R., Mohammadian A., Kheirkhah G. H. A comparison of standard k-ε and realizable k-ε turbulence models in curved and confluent channels [J]. Environmental Fluid Mechanics, 2018, 19(2): 543–568.
Ramos P. X., Schindfessel L., Pêgo J. P. et al. Influence of bed elevation discordance on flow patterns and head losses in an open-channel confluence [J]. Water Science and Engineering, 2019, 12(3): 235–243.
Zhang J. T., Su X. H. Numerical model for flow motion with vegetation [J]. Journal of Hydrodynamics, 2008, 20(2): 172–178.
Stoesser T., Liang C., Rodi W. et al. Large eddy simulation of turbulent flow through submerged vegetation [J]. Transport in Porous Media, 2009, 78: 347–365.
Li C. W., Zeng C. 3D Numerical modelling of flow divisions at open channel junctions with or without vegetation [J]. Advances in Water Resources, 2009, 32: 49–60.
Huai W. X., Li C. G., Zeng Y. H. et al. Curved open channel flow on vegetation roughened inner bank [J]. Journal of Hydrodynamics, 2012, 24(1): 124–129.
Huai W., Wang W., Hu Y. et al. Analytical model of the mean velocity distribution in an open channel with double-layered rigid vegetation [J]. Advances in Water Resources, 2014, 69: 106–113.
Brito M., Fernandes J., Leal J. B. Porous media approach for RANS simulation of compound open-channel flows with submerged vegetated floodplains [J]. Environmental Fluid Mechanics, 2016, 16(6): 1247–1266.
Ozan A. Y. Flow structure at the downstream of a one-line riparian emergent tree along the floodplain edge in a compound open-channel flow [J]. Journal of Hydrodynamics, 2018, 30(3): 470–480.
Chang K., Constantinescu G., Park S. 2-D eddy resolving simulations of flow past a circular array of cylindrical plant stems [J]. Journal of Hydrodynamics, 2018, 30(2): 317–335.
Wang W. J., Peng W. Q., Huai W. X. et al. Roughness height of submerged vegetation in flow based on spatial structure [J]. Journal of Hydrodynamics, 2018, 30(4): 754–757.
Shan Y., Huang S., Liu C. et al. Prediction of the depth-averaged two-dimensional flow direction along a meander in compound channels [J]. Journal of Hydrology, 2018, 565: 318–330.
Yang Z. H., Bai F. P., Huai W. X. et al. Lattice Boltzmann method for simulating flows in open-channel with partial emergent rigid vegetation cover [J]. Journal of Hydrodynamics, 2019, 31(4): 717–724.
Huai W., Yang L., Wang W. et al. Predicting the vertical low suspended sediment concentration in vegetated flow using a random displacement model [J]. Journal of Hydrology, 2019, 578: 124101.
Huai W. X., Zhang J., Katul G. G. et al. The structure of turbulent flow through submerged flexible vegetation [J]. Journal of Hydrodynamics, 2019, 31(2): 274–292.
Li C. W., Busari A. O. Hybrid modeling of flows over submerged prismatic vegetation with different areal densities [J]. Engineering Applications of Computational Fluid Mechanics, 2019, 13: 493–505.
Zhang M. L., Li C. W., Shen Y. A 3D non-linear k-ε turbulent model for prediction of flow and mass transport in channel with vegetation [J]. Applied Mathematical Modelling, 2010, 34(4): 1021–1031.
Yakhot V., Orszag S. A., Thangam S. et al. Development of turbulence models for shear flows by a double expansion technique [J]. Physics of Fluids A, 1992, 4(7): 1510–1520.
Brackbill J. U., Kothe D. B., Zemach C. A continuum method for modeling surface tension [J]. Journal of computational physics, 1992, 100(2): 335–354.
Gao Y., Huang S., Li Q. Experimental research on velocity distribution along depth at junction of bend stream with branch afflux [J]. Water Resources and Power, 2012, 30(7): 90–93.
Tominaga A., Nagao M., Nezu I. Effects of vegetation on flow structures and bed profiles in curved open channel [C]. Proceedings of 2nd International Symposium on Environmental Hydraulics, Hong Kong, China, 329–334.
Dutta P., Saha K. S., Nandi N. Numerical study of curvature effect on turbulent flow in 90° pipe bend [C]. Proceedings of Sixth International Conference on Theoretical Applied Computational and Experimental Mechanics, Kharagpur, West Bengal, India, 2014, 44–45.
Author information
Authors and Affiliations
Corresponding author
Additional information
Projects supported by the National Natural Science Foundation of China (Grant No. 51739011), the National Key Research and Development Program of China (Grant No. 2016YFC0402707-03).
Biography
Zheng-rui Shi (1993-), Male, Ph. D. Candidate, E-mail: 18135656397@163.com
Rights and permissions
About this article
Cite this article
Shi, Zr., Ai, Cf. & Jin, S. 3-D numerical simulation of curved open channel confluence flow with partially non-submerged rigid vegetation. J Hydrodyn 33, 992–1006 (2021). https://doi.org/10.1007/s42241-021-0088-7
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s42241-021-0088-7